1. Field of the Invention
This invention relates to mycology, more specifically, to a process for the production of inoculants for herbaceous plants and to the inoculants so produced.
2. Prior Art
As noted above, this invention relates to mycology, and the momenclature used is intended to be consistent with Snell and Dick, A Glossary of Mycology, Harvard U. Press, Cambridge, Mass. (1957).
Mycorrhizae are symbiotic associations between the hyphae of certain fungi and the absorbing organs-typically the roots of plants. They are classified according to the manner in which the fungus infects the root. The two main types are ectomycorrhizae in which fungal hyphae penetrate the intercellular spaces between root cells without entering the interior of the cells, and endomycorrhizae where projections of the fungus enter the interior of the cell.
Ectomycorrhizae are generally associated with trees and other woody species and are formed by "higher fungi" that are found in a number of families of basidiomycetes and ascomycetes. In ectomycorrhizae, the normal branching pattern in the roots is changed. Roots infected with ectomycorrhizal fungi are short, swollen, branched and lack root hairs.
Endomycorrhizae are generally associated with herbaceous plants such as grasses, corn, onions and many more, however there are some trees that also form endomycorrhizae. Endomycorrhizae are formed from spores produced by "lower fungi," classified as zygomycetes, and belong to one family, the Endogonales. The fungi that produce these spores are unknown. From the outside, the infected roots look normal, and the only way to detect the infection is by microscopic examination. Then one can see that the hyphal projections of the fungus have invaded the cells forming small branches (arbuscles) and/or swellings at tips of some hyphae (vessicles). Many endomycorrhizae are called "Vessicular-Arbuscular Mycorrhizae" or VAM, because of the presence of vessicles and arbuscles inside root cells. Ectomycorrhizae do not have vessicles or arbuscles.
Ectomycorrhizal fungal inoculants for woody plants such as pine have been produced. See, for example, Litchfield et al., U.S. Pat. No. 4,327,181, "Aerobic Submerged Fermentation of Sporulating Ectomycorrhizal Fungi" (1982) disclosing liquid culture of selected fungi for broadcast over forest soil. Marx et al., "Growth and Ectomycorrhizal Development of Loblolly Pine Seedlings in Fumigated Soil Infested with the Fungal Symbiont Pisolithus tinctorium," Forest Science Vol. 22 No. 3, pp. 245-254 (1975), show the use of Pisolithus tinctorius cultured in an agar/vermiculite/peat moss medium in forest nurseries. See also Mosse et al., U.S. Pat. No. 4,294,037, "Production of Mycorrhizal Fungi" (1981) and Warner, U.S. Pat. No. 4,551,165, "Mycorrhizal Seed Pellets" (1985).
As far as known, however, inoculants suitable for leafy plants such as wheat or the common vegetables corn, onion, asparagus and the like have not heretofore been produced. Compare Watrud, "Spore Germination and Axenic Culture of Endomycorrhizae," writing at page 81 of Methods and Principles of Mycorrhizal Research, the American Phytopathological Society (1982): ". . . To date, successful axenic subculture of hyphae of vesicular-arbuscular mycorrhizae has yet to be reported. . . ." See also Hudson, Fungal Biology, pp. 218 and 219, Edward Arnold (1986); Smith and Douglas, The Biology of Symbiosis, pp. 152 and 153, Edward Arnold (1987); and Mugnier et al., U.S. Pat. No. 4,599,312, "Method of Producing Endomycorrhizian Fungi with Arbuscules and Vesicles in Vitro" (1986).